A wide variety of applications require an array of cells electrically connected together to provide a battery system having the requisite electrical performance characteristics. Such applications, sometimes termed industrial battery applications, include stationary battery applications in which the cells and batteries, typically lead-acid cells and batteries, provide stand-by power in the event of a power failure. For this type of application, such cells and the resulting batteries are maintained at a full state-of-charge and in a ready-to-use condition, typically by floating at a constant preset voltage. Stationary batteries are used for stand-by or operational power in a wide variety of applications, including, by way of illustration, telecommunications, utilities, for emergency lighting in commercial buildings, as stand-by power for cable television systems, and in uninterruptible power supplies for computer back-up power and the like.
Other industrial battery applications in which lead-acid cells and batteries may be used involve a variety of motive power applications in which an array of cells or batteries provides the motive power for vehicles ranging from Class 1 to Class 3 trucks, various automated guided vehicles, mining vehicles, and also railroad locomotives.
The electrical performance requirements dictate that the array of cells which must be electrically connected together be tailored to the specific application. Thus, for example, the number of cells involved may vary from 6 or 12 up to over 100 or more. Such cells can be electrically connected in series, in parallel, or in both, depending upon the particular requirements of the application.
Fundamental to the process of using lead-acid cells for such industrial battery applications is the necessity of making efficient cell-to-cell electrical connections, i.e., connecting the terminals of adjacent cells. Typically, a pre-cast lead connector is manually placed over the terminal posts in adjacent cells which are to be electrically connected. Some form of a mold is then manually placed in position, and then the connection is made by fusion with a gas torch or by other means, such as by induction heating or the like. The molds are then manually removed and an insulating plastic shroud is placed over the connectors for aesthetic and safety reasons.
As may be appreciated, this method of making the cell-to-cell connection is extremely labor intensive and is not amenable to continuous or even semi-continuous processing. Moreover, extreme care must be taken to at least minimize molten lead leaks, run-downs and the like while the connection is being made. More particularly, fusion to provide the satisfactory post-to-connector electrical connection requires the parts being fused to have their respective surfaces be adequately molten so that appropriate fusion takes place; yet, current methods, as far as can be ascertained, make it difficult to maintain the molten lead in place and to avoid molten lead leaking down onto the cells.
There thus exists the need for a more efficient method of making the required cell-to-cell electrical connections. Given the relatively large number of such connections which are required, tailored to the particular application, the need is clear and is substantial.
It is accordingly an object of the present invention to provide a more effective and efficient method for making the cell-to-cell connections for lead-acid cells and batteries.
Another object of this invention provides a method for making such cell-to-cell connections which is more amenable to automation.
Yet another object of this invention lies in the provision of a method which minimizes the likelihood of leaks and the like resulting from effecting the necessary post-to-connector operation.
A still further object of this invention in a more preferred embodiment is to provide a method which avoids the need for separately providing an insulating plastic shroud.
Other objects and advantages of the present invention will be apparent as the following description proceeds.